1. Field
The invention is in the field of hydraulically operated devices to restrain movement of the cab of a tractor-trailer, automotive, transport truck that has its cab pivoted to be swung between maintenance and operational position relative to the engine of the tractor.
2. State of the Art
Mechanical latching devices are currently used to hold the cab of a tractor-trailer truck in operational position as the truck travels down the road, see, for example, Brimhall U.S. Pat. No. 3,797,882, Nordell et al. U.S. Pat. No. 3,752,519, and Kimball U.S. Pat. No. 4,159,136. The aforementioned patents feature a mechanical latch having an elongate, pivoted, hooked latching member which engages a keeper bar and is held in engaged latched position by action of a compression spring. A latch of this type does not eliminate all relative movement between the tractor chassis and the cab, and, although the compression spring tends to soften some of this relative movement, such movement still provides an uncomfortable ride for those in the cab and results in jarring impacts of the cab.
Some attempts have been made to incorporate an air spring between the tractor chassis and the cab to improve the ride. Such attempts have used a standard latch and bracing between the cab and tractor chassis to prevent relative lateral movement between the two.
The need for improvement in the ride of cab-over-engine truck tractor units remains despite the existence of air spring suspension systems. There are currently no devices available that combine a suspension system with means for keeping the cab in operational position.